So you can simply change the port 4502 to a new port for example 4512, and start the proxy.jar with the following command:

> java -jar proxy.jar localhost 4502 4512 -logfile proxy.log

This will open a port to listen on port 4512 and redirect it to 4502, so that all communication is then logged in the proxy.log (make sure you restarted the webserver for the dispatcher.any changes to take effect).

Later you can use this information to find more details about what could be the issue (for example your SSO is not properly configured and so you dont get the correct header in the request).